Background: Increasing evidence from clinical studies suggests an association between obstructive sleep apnea (OSA) and insomnia, with the prevalence of this comorbidity ranging from 39% to 58%. Further, comorbid insomnia has emerged as an important clinical factor that can worsen adherence to Positive Airway Pressure (PAP) treatment, which is the first-line of treatment for patients diagnosed with OSA. Although these findings provide important insight, they are not without limitations. First, the variability n the prevalence of comorbid insomnia and OSA results from methodological limitations in assessing insomnia symptoms, including a failure to use validated tools. Second, existing studies are largely conducted in homogenous samples, making it impossible to assess racial/ethnic disparities, which is a growing concern in understanding poor adherence to PAP treatment. Research: The proposed study within this K-Award, which will be the first step in a larger program of research to identify factors that contribute to poor adherence to PAP treatment, and how these differ between black and white patients. This will ultimately (1) enable clinical profiling of individuals with comorbid insomnia and OSA, (2) determine whether black patients diagnosed with OSA differ from their white counterparts with respect to adherence to PAP treatment, and (3) determine whether [comorbid insomnia] mediates the relationship between [race/ethnicity and poor adherence to PAP treatment] above and beyond patient and contextual factors. The proposed study will leverage the resources of the NYU and Weill Cornell Sleep Disorders Center to recruit [108] patients recently diagnosed with OSA, based on polysomnography, the gold standard for diagnosing OSA. Of these, [54 will present with comorbid insomnia and 54 without comorbid insomnia]. Polysomnography will be coupled with [a clinical interview by trained staff at the sleep clinic to classify insomnia symptoms along with the Insomnia Severity Index, and actigraphically-derived sleep data anchored by a 7-day sleep diary] and objective data for adherence to PAP treatment. The primary outcome for the study is adherence to PAP over 6 months. Training: This component of the K23 is composed of the didactic and mentored experiences required to develop the proposed program of research. The training plan builds upon my background and experience in health education with minority populations, and will provide me with the necessary training in sleep research, [epidemiology], behavioral sleep medicine, conduct of innovative health interventions, and quantitative skills. The pedagogical approach includes one-on-one mentorship, course work, mentored laboratory training, and attendance of targeted conferences and seminars, all with the common goal of supporting my transition to become an independent investigator.